docstr: Returns whether the caching phase is done.
docstr_tok: ["Returns","whether","the","caching","phase","is","done","."]
code: def filled(self) -> bool:
      """Returns whether the caching phase is done."""
      if self._is_done:
          return True
      self._is_done = os.path.exists(
          os.path.join(self._cache_dir, _INDEX_FILENAME)
      )
      return self._is_done
  
imports: import logging
  import os
  from dataclasses import dataclass
  from typing import Any, Dict, List, Optional, Tuple, Union
  from lightning.data.streaming.constants import _INDEX_FILENAME, _LIGHTNING_CLOUD_LATEST, _TORCH_GREATER_EQUAL_2_1_0
  from lightning.data.streaming.item_loader import BaseItemLoader
  from lightning.data.streaming.reader import BinaryReader
  from lightning.data.streaming.sampler import ChunkedIndex
  from lightning.data.streaming.serializers import Serializer
  from lightning.data.streaming.writer import BinaryWriter
  from lightning.data.utilities.env import _DistributedEnv, _WorkerEnv
  from lightning.data.utilities.format import _convert_bytes_to_int
label_desc: Use image node_id 3 for calling the Cache obj's underlying member method code with example usage: obj.filled() and returns: self, True